/*
 * dcMotor.c
 *    A program that turns turns the dcMotor, first clockwise, then
 *    counter-clockwise
 *
 * Author: C.Schramm
 * Date: February 10, 2006
 */

#define _IO_BASE        0
#define _ADDR(off)      (unsigned char volatile *)(_IO_BASE + off)
#define _P(off)         *(unsigned char volatile *)(_IO_BASE + off)
#define DDRP    _P(0x025A)
#define PTP     _P(0x0258)

#define PWME     _P(0xA0)
#define PWMPOL   _P(0xA1)
#define PWMCLK   _P(0xA2)
#define PWMPRCLK _P(0xA3)
#define PWMCAE   _P(0xA4)
#define PWMCTL   _P(0xA5)
#define PWMSCLA  _P(0xA8)
#define PWMSCNTA _P(0xAA)

#define PWMCNT7  _P(0xB3)
#define PWMPER7  _P(0xBB)
#define PWMDTY7  _P(0xC3)

#define PORTK    _P(0x32)
#define DDRK     _P(0x33)

void delay(int n);

void main(void)
{
	int duty, i, fanDuty;
	int maxSpeed;

	// DO NOT ALTER THE INITIALIZATION CODE
	//Setup PWM Control of Motor
	//Output for all channels is high at beginning 
	//of Period and low when the duty count is reached

	PWMPOL = 0xFF;
	PWMCLK |= 0x10;			//Select Clock SB for channel 7
	PWMPRCLK = 0x70;		//Prescale ClockB by busclock/128
	PWMSCLA = 0;			//Total Divide: EClock/512
	PWMCAE &= 0x7F;			//Make sure Chan7 is in left aligned output mode
	PWMCTL &= 0xF3;			//Allow PWM in Wait and Freeze Modes
	PWMPER7	= 100;			//Set period for PWM7
	PWME = 0x80;			//Enable PWM Channel 7

	DDRP |= 0x60;  		  // So we can set the Motor Direction Control	
		 				  // NOTE: We have a conflict: Lightbar will also turn on.
    DDRK |= 0x0F;		  // So we can use LEDs as messages.
	// END OF INITIALIZATION CODE.
	
	// Turn on DC motor in clockwise direction, with given maxSpeed.

	maxSpeed = 20;	  	// YOU MAY CHANGE THIS VALUE
			   			// WARNING: NEVER SET maxSpeed TO MORE THAN 35. 
			   			// IT WILL DAMAGE THE MOTOR.
						// TIP: NEVER SET maxSpeed TO LESS THAN 20. 
						// IT WON'T GO THAT SLOW!
						
	// Select direction using Port P, Bit 6 (1=Clock wise,0=Counter-Clockwise)	
	PTP = 0b00000000;
 
    // LEAVE THE REST OF THE CODE UNTOUCHED. READ IT TO SEE WHAT TO EXPECT
	// Turn motor on **incrementally** until reached maxSpeed.
	PORTK = 0b00000001;		// Turn on RED LED for speedup	
	for(duty = 10; duty <= maxSpeed; duty++)
	{
		PWMDTY7 = duty; delay(4);
	}	
	
	PORTK = 0b00000010;		// Turn on WHITE LED for steady-speed	
	delay(40);	  // Let motor run for a little while.
		
	// Turn off motor (incrementally) -- slow braking	
	PORTK = 0b00001000;		// Turn on YELLOW LED for braking	
	for(duty = maxSpeed; duty >= 0; duty--)
	{
		PWMDTY7 = duty; delay(4);
	}	
	PORTK = 0b00001000;		// Turn on GREEN LED for done	
}
	
/* delay
 *   Does idle work for a period of time, keeping the CPU busy
 *   but doing nothing useful
 */
void delay(int n)
{
	int x;
	int y;
	int dummy = 1000;
	for (;n>0;n--)
	{
	 for(y=0; y<0x1F; y++)
	 {
	  for(x=0; x<0x1FF; x++)
	  {
		dummy = dummy + 0;
		dummy = dummy * 1;
		dummy = dummy / 1;
	  }
	 }
	}
}